WELCOME

SEMINAR ON

REPRODUCTION

Presented by

MUHAMMAD SHAFI CBABINA K DHANYA E K LIJINA K V

P.R.N.S.S COLLEGE

MATTANUR

2010-2011

INTRODUCTION

Ability of living organisms to produce young ones similar to themselves is called reproduction.

In sexual reproduction testis is the male sex organ, ovary is the female sex organ.

Formation of gametes for sexual reproduction is called gametogenesis.

Human reproductive cycle is called menstrual cycle.

Testis are the primary male sex organ.

They produce sperms and secrete male sex hormone called testosterone.

Mammalian testis are a pair of ovoid structure.

They are suspended in a pouch out side the abdomen called scrottum.

STRUCTURE OF MAMMALIAN TESTIS

Testis enclosed by a thick fibrous capsule the Tunica albuginea..

Posterior margin of the tunica is thickened to form the Media sternum.

Each testis is divided to 200-300 lobules.

Extending in to the lobule are long slender and convoluted tubules called Seminiferous tubules.

The seminiferous tubules lie embedded in the connective tissue interspersed with the interstitial cells or leydig cells.

SECTION OF

SEMINIFEROUS TUBULES

The seminiferous tubules unite to form several stright tubules which open in to irregular cavities called rete testis.

Arising from the rete testis is a series of fine tubules called vasa efferentia

These are bundled in connective tissue and jointed together to form highly convoluted tube called epidymis.

The germinal epithelium of seminiferous tubules consist of sertoli cells.

It provide shape and nourishment to the developing spermatogenic cells.

MAMMALIAN OVARY

STRUCTURE OF

Ovaries are primary female sex organs produce ova and female sex hormones namely oestrogens and progesterones.

Human ovaries are pinkish grey in colour and are suspended from the vertebral column by mesovarium at the level of utereus.

STRUCTURE

OF

A

MAMMALIAN OVRY

Central portion of ovary-Medulla.

Outer layer-Cortex.Cortex contain ovarian follicles.The mature ovarian follicle of mammals is called graffian follicle.

Microscopically ovary consist of four regions,

1. Germinal epithelium. 2.Capsule of connective tissue. 3.Stroma of connective tissue internal to the capsule.

4.Ovarian follicles.

The Oogonia undergo multiplication and the majority of them differentiate to the prophase stage as primary oocytes by fourth or fifth foetal month.

After menopause primary oocytes of the ovary degenerate and disappear

Degeneration of follicle is known as atresia

PRIMARY FOLLICLE

Primary follicle consist of an oocyte sarrounded by single layer of flattened cells called follicular cells.

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PRIMARY FOLLICLE

A fluid filled cavity is called antrum developed within the follicle.

The fluid fill the antrum is known as liquor folliculi.

GERM HILLThe ovum is pressed to one side where it is sarrounded by follicular cells projecting in to the antrum. These cells are called germ hill or cumulus oophorus.

It arrange themselves to form corona radiata.

The antrum has a regular epithelial lining called Membrane granulosa.

Which rests on a homogenous basement membrane called Glassy membrane.

SEMEN PRODUCTION AND OVULATION

GAMETOGENESISFormation of haploid gametes from the diploid germ cells.

It involves three stages; 1.Multiplication phase. 2.Phase of growth 3.Phase of maturation

Spermatogenesis

Formation of sperms from the primordial germ cells

A .Formation of spermatids

B.Spermiogenesis

SUMMARY OF

SPERMATOGANESIS

B.Spermiogenesis*Metamorphosis of the spermatids in

to sperm by differentiation*Golgibodies-Acrosome(Golgibodies→Acroblast→Acrosomal

granules.Acrosomal granules fills the whole acroblasts)

*Mitochondria, two centrioles→Middle piece

*Whip like posterior part→Tail

Oogenesis Formation of egg or ova from the primordial germ cells of the germinial epithelium in ovaries.

SUMMARY OF OOGENESIS

SPERMMale gamete.Activates the egg to initiate development.

Contribute a haploid set of chromosomes.

It is a tadpole like motile units with long tail.Discovered Leeuwenhoek in 1677. M

AMMALIAN

SPERM

STRUCTURE

OF

OVUMIt is a female gameteIt supplies haploid set of chromosomes

It contributes allmost all cytoplasm to the zygote

Supplies food to the developing embryo

SHAPE AND SIZESize depends on amount of yolk

Smallest egg –Mouse(0.07mm)

Eggs are spherical or ovoid in shape

Largest egg-Ostrich(85 mm)

STRUCTURE OF EGG

SEMINATION AND OVULATION SEMINATION Releasing of mature spermatozoa from the testes

OVULATION

Rupture of graafian follicle with the release of ovum in to the coelom is called ovulation

GRAAFIAN FOLLICLE

CORPOUS HAEMORRHAGICUM ●The ruptured follicle gets filled with clotted

blood called corpus haemorrhagicum.●The follicular cavity close over the

ruptured part by healing of the wound.●It becomes filled with serous fibrin

containing fluid replacing the blood cloat and increase greatly in size. These cells are called granulosa lutien cells.

CORPOUS LUTEUMUnder the influense of lutinizing hormone grannulosa lutein cells become deposited with fine lipid droplets and an yellow carotenoid pigments wich imparts an yellow colour to the corpous.

LUTENISATION

Formation of corpous luteium from ruptured follicle.

Corpous luteium function as endocrine gland wich secreate the hormone called progesterone.

CORPOUS ALBICANS

If pregnancy does not take place the corpous luteum degenerates to form a white fibrous mass of tissue known as corpus albicans.

MENSTRUAL CYCLE

In primates reproductive cycle begins in the females at the time of puberty

These sexual cycles occur at two levels in the reproductive system

1. Ovarian cycle 2.menstrual cycle

OVARIAN CYCLEThe cyclical changes which occur in the ovary

Three major phase 1. Follicular phase 2.Ovulation phase 3. Luteal phase

STRUCTURE OF HUMEN OVARY TO SHOW THE OVARIAN CYCLE

1. FOLLICULAR PHASEFollicle stimulating hormonePrimary follicle Graffian follicle Graffian follicle secrete oestrogensOestrogen stimulate the production of LH and

inhibit the production of FSH.Follicular antrumCumulous oophorous

When follicle mature resumes its meiotic division

2. Ovulation phase

With the help of luteinizing hormone graffian follicle ruptures and ovulation with the help of FSH and LH.

3.Luteal phase

Collapsed follicle→Corpous luteum.Corpus luteum secrete Progesterone.Progesterone inhibits FSH production and prevents further follicular maturation if pregnancy occurs.

In the absence of pregnancy corpus luteum degenerates.

UTERIN CYCLEThe cyclical changes occurs in the uterous.

Three major phases 1.Menstrual phase 2.Pre-ovulatory phase 3.Post ovulatory phase

1. Pre ovulatory phase

It is the stage between menstruation and ovulation

FSH and LH stimulates the ovarian follicles to produce more estrogens

Proliferation of endometrial cells

2 Post-ovulatory phase Corpus luteum disappears, progesterone secretion stops, endometrium collapses, menstruation follows.

Period between ovulation and the onset of next menses

3.Menstrual phaseDischarge of blood,tissue fluid mucus and endometrial cells

MensesThin endometrium→Thick vascular and glandular endometrium.

CHANGES DURING MENSTRUAL CYCLE

HYPOTHALAMUS-PITIUTARY OVARIRNAXIS OFHORMONAL CONTROL OF MENSTRUAL CYCLE

Menarche and Menopause

Menarche - First menses that occurs on attaining puberty

Menopause – Last menses with which the menstrual cycles ceases

1. Animal physiology-Mohan P Arora2. Animal physiology-K K Bhaskaran3. Developmental biology- Vijaya

kumaran Nair

REFERENCE

THANKS